German public broadcaster WDR 2 on Saturday issued an apology for showing a video of a children's choir singing a humorous, traditional tune rewritten with satirical lyrics.

The song, titled "My grandma is an old environmental pig," triggered heated reactions on Twitter. One user described the lyrics as "disrespectful," while a WDR news editor said the remake of the traditional tune was "scandalously good."

The lyrics, including verses about grandma riding a motorcycle that burns a thousand liters of gasoline every month and eating a cutlet every day because meat from the discount supermarket is so cheap, include the refrain, "My grandma is an old environmental pig." The video ends with a quote from teenage climate activist Greta Thunberg: "We will not let you get away with this."

WDR Twitter accounts responded to some of the tweets, saying: "The video should not be considered offensive."

Read more: Germany: From leader to loser on climate protection?

However, that didn't stop the broadcaster from deleting the video from its website.

"We are concerned by the allegation that the children involved may have been 'instrumentalized,'" said WDR 2 in a statement published on Facebook. "This is absolutely not the case, but we decided to delete the video."

"The assumption that WDR had 'instrumentalized' the children of the choir is unbearable for the editorial staff."

The man-made destabilization of Earth's climate system has become a rallying cry for youths following the global spread of student-led climate justice protests spearheaded by Swedish activist Greta Thunberg.

Read more: Should private jets be banned to spare the climate?

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ls/sms (dpa, ARD)